Receiving and Detection of Ultra-Wideband Microwave Signals Radiated by Pulsed Excitation of Monopole Antennas

Pulsed excitation of small size monopole antennas for generating wideband electromagnetic pulses was used. The monopoles were excited by electrical pulses having rise times of 600 ps, 200 ps, 70 ps and voltages 100 V, 15 V, and 0.4 V respectively. Antennas spanning (0.3-26) GHz bandwidth, including broadband horns with coaxial outputs, were employed to receive signals, which were investigated using (0-26) GHz passband sampling oscilloscope. It was found that waveforms of signals, received by the antennas, mostly depend on the pulse rise time and on the details of geometry of monopoles. The electromagnetic pulses have relatively long duration of about 30 ns and spectral harmonics up to 22 GHz. Therefore they can be attributed to pulses with large base. The results show that the upper frequencies of the spectrum most probably are cut off by existing arrangement. Usage of such pulses can find wide practical application when they are received after transmission trough different media by a number of antennas having different operational frequency ranges, followed by digital signal processing.Original Abstract: Nedideliu monopoliniu antenu impulsinis suzadinimas buvo panaudotas placiajuosciu elektromagnetiniu impulsu generacijai. Suzadinimas vykdomas elektriniais videoimpulsais, kuriu frontai 600 ps, 200 ps, 70 ps, o amplitudes atitinkamai 100 V, 15 V ir 0,4 V. Placiajuostes antenos, tarp kuriu buvo ruporines antenos, turincios bendraasi isejima ir perklojancios 0,3 GHz-26 GHz ruoza, buvo panaudotos signalams priimti. Sie signalai buvo nagrinejami stroboskopiniu oscilografu, turinciu 0 GHz-26 GHz pralaidumo juosta. Taip pat buvo realizuota signalu detekcija, naudojant placiajuoscius stiprintuvus ir skirtingo tipo detektorius. Po priimtu signalu vizualizacijos aptikta, kad ju forma priklauso nuo suzadinamojo impulso fronto statumo ir maziau nuo monopoliu geometrines formos detaliu. Isspinduliuoti placiajuosciai elektromagnetiniai impulsai turi santykinai didel$ trukme - apie 30 ns, o ju spektro harmonikos pleciasi iki 22 GHz. Tokius impulsus galima priskirti impulsams su didele baze. Baze yra impulso trukmes ir jo juostos plocio sandauga ir visada gerokai virsija vieneta, aptariamuoju atveju ji yra apie 600. Rezultatai rodo, kad virsutines spektro harmonikos dar nera matomos, nes nupjautos naudojama eksperimentine iranga. Praktiniams taikymams tokie impulsai panaudojami, jei po isspinduliavimo prasiskverbia pro terpes, turincias skirtingas daznines savybes, pvz.,